package com.hmdp.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.entity.Shop;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.*;

@Component
@Slf4j
public class CacheClient {
    private final StringRedisTemplate stringRedisTemplate;

    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);


    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public void set(String key, Object value, Long time, TimeUnit unit){
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(value),time,unit);
    }

    public void setWithLogicalExpire(String key, Object value, Long time, TimeUnit unit){
        //设置逻辑过期
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        //存入redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(redisData));
    }

    public <R,ID> R queryWithPassThrough(
            String keyPredix, ID id, Class<R> type, Function<ID,R> dbFallback,
    Long time, TimeUnit unit){
        String key = keyPredix+id;
        //从redis查询商铺缓存
        String json = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isNotBlank(json)) {
            //存在，直接返回
            return JSONUtil.toBean(json, type);

        }
        //判断是否是空值
        if (json != null){
            return null;
        }

        //不存在，查询数据库
        R r = dbFallback.apply(id);
        if (r==null){
            //把空值写入redis
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
            //不存在，返回错误
            return null;
        }
        //存在，写入redis
        this.set(key,r,time,unit);
        return r;
    }


    public <R,ID> R queryWithLogicalExpire(String keyPredix, ID id,Class<R> type,Function<ID,R> dbFallback,
                                           Long time, TimeUnit unit) {
        String key  = keyPredix+id;
        //从redis查询商铺缓存
        String json = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isBlank(json)) {
            //不存在，直接返回null
            return null;
        }
        //把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
        R r = JSONUtil.toBean((JSONObject)redisData.getData(),type);
        LocalDateTime expireTime = redisData.getExpireTime();

        //判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //未过期，直接返回
            return r;
        }
        //已过期，进行缓存重建
        //获取互斥锁
        boolean trylock = trylock(LOCK_SHOP_KEY + id);
        if (trylock) {
            //再次判断是否过期
            String json1 = stringRedisTemplate.opsForValue().get(key);
            RedisData redisData1 = JSONUtil.toBean(json1, RedisData.class);
            LocalDateTime expireTime1 = redisData1.getExpireTime();
            if (expireTime1.isAfter(LocalDateTime.now())) {
                //未过期，直接返回
                return r;
            }
            //获取互斥锁成功，开启独立线程进行缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                //重建缓存
                try {
                    R r1 = dbFallback.apply(id);
                    this.setWithLogicalExpire(key,r1,time,unit);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //释放锁
                    deleteLock(LOCK_SHOP_KEY + id);
                }
            });
        }

        //获取互斥锁失败，返回商品信息（过期）
        return r;
    }
    private boolean trylock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);

    }

    /**
     * 释放互斥锁
     * @param key
     */
    private void deleteLock(String key){
        stringRedisTemplate.delete(key);
    }
}
